This invention relates generally to electromagnetic actuators and more particularly to limited motion rotary devices used to drive mirrors in optical deflection systems.
A wide variety of such actuators exist for a corresponding number of specialized applications. Because these applications tend to require (1) low power or, (2) high Q at the resonant frequency or (3) large deflection angles or (4) large force or torque, there is no existing device which satisfies the needs of an actuator for an optical system useful in reading small labels affixed to packages (manufacturing ease). In this type of application, power requirements are not critical. Since the frequency of operation is fixed by the rest of the system and near the designed resonance of the device a high Q device is not desirable. Moderate deflection angles are entirely adequate and very little force is required.
On the other hand, the device must have a very long life and not be subject to failure. It should be easily manufactured, assembled, adjusted and tested. No materials should be used which require special processing or exceptional handling. The device should be physically rugged, able to withstand shocks, heat, humidity, and dust without adverse effects on its operation or life. It should be largely insensitive to the effect of heat and not dissipate much heat even during continuous operation. The production of large quantities of such devices should be easily accomplished without special skills, techniques or tools. Adjustments for resonant frequency and Q should be provided to accommodate larger tolerances in the manufacturing process. These adjustments should be easily made and hold their value for the life of the device.